UPDATE 4-US Justice Dept probes airline ticket sellers--AMR

* American says gov't investigating ticket sellers

* Airline promises to cooperate with antitrust probe

* Airlines have filed suits against ticket-sellers

* Sabre says it also contacted, cooperating (Adds DOJ comment)

CHICAGO/WASHINGTON, May 20 (Reuters) - The U.S. Justice Department's antitrust division is probing whether third-party ticket-sellers violated antitrust law, with American Airlines, US Airways Group Inc (LCC.N) and Travelocity owner Sabre saying they have been contacted as part of the investigation.

Neither the Justice Department nor any of the companies involved in the investigation would provide specific information on the probe.

"The antitrust division is investigating the possibility of anti-competitive practices in the global distributions industry," said Justice Department spokeswoman Gina Talamona.

Cost-conscious airlines have been at odds with some online travel agents over distribution costs and methods.

AMR Corp AMR.N, parent of American Airlines, said on Friday it would cooperate with the investigation.

"American welcomes this investigation by the Department of Justice and intends to cooperate fully," the carrier said in a statement.

Sabre Holdings Corp [TSG.UL] said it had also been contacted.

"Yes, the U.S. Department of Justice has contacted us as we believe they have contacted others as well. We are cooperating fully," spokeswoman Nancy St. Pierre said in an email.

American Airlines filed a lawsuit last month accusing Orbitz Worldwide Inc (OWW.N) and air fare data provider Travelport of making American's fares look higher to customers than they were. It is also battling Sabre, which owns Travelocity, over how its fares are presented.

American stopped listing its fares on Orbitz last year after the travel agency refused to adopt new American technology that would let people price their trips based on factors other than just fares.

In April, US Airways Group Inc (LCC.N) filed a lawsuit against Sabre, accusing it of making it difficult for travel agents to book tickets directly with airlines and forcing US Airways to accept its terms in an agreement the two signed in February.

More than 35 percent of US Airways' revenue is booked through Sabre and Sabre-affiliated travel agents, the airline said.

Airlines, clawing their way out of an economic downturn that drained travel demand, have also been targeting distribution costs -- a relatively low-ranking expense for major airlines, whose top two expenses are fuel and labor.

A Justice Department antitrust investigation would likely take at least a year to resolve and opens a second legal front in the airlines' battle with ticket-sellers.

Orbitz declined to comment. A spokeswoman for Travelport did not return telephone calls seeking comment. (Reporting by Kyle Peterson and Diane Bartz; editing by Gerald E. McCormick, Steve Orlofsky and Andre Grenon)